Cantaloupe rinds could be one reason behind a recent salmonella outbreak linked to the fruit, according to food safety experts.

The melon’s rough rinds contain crags where tiny salmonella bacteria can attach itself, which, experts say, separates cantaloupes from other produce.

“It’s much easier to scrub the surface of a honeydew melon than it is to scrub the surface of a cantaloupe and actually remove microorganisms that are on the surface,” said Linda Harris, a food safety specialist at the University of California at Davis.

Harris says other factors like contaminated water, soil, or even kitchen utensils can transmit the bacteria onto cantaloupe.

Experts urged people to thoroughly clean all produce—but said there’s no way to totally ensure food safety.

“I think it’s appropriate to be careful, but there’s no completely fail-safe measure that consumers can take,” said Ferric Fang, a microbiologist at the University of Washington.

Last week, the Centers for Disease Control and Prevention reported at least two deaths from this most recent outbreak and 17 cases in Illinois.